.TH std::logic_error 3 "2024.06.10" "http://cppreference.com" "C++ Standard Libary"
.SH NAME
std::logic_error \- std::logic_error

.SH Synopsis
   Defined in header <stdexcept>
   class logic_error;

   Defines a type of object to be thrown as exception. It reports errors that are a
   consequence of faulty logic within the program such as violating logical
   preconditions or class invariants and may be preventable.

   No standard library components throw this exception directly, but the exception
   types std::invalid_argument, std::domain_error, std::length_error,
   std::out_of_range, std::future_error, and std::experimental::bad_optional_access are
   derived from std::logic_error.

   std-logic error-inheritance.svg

                                   Inheritance diagram

.SH Member functions

   constructor   constructs a new logic_error object with the given message
                 \fI(public member function)\fP
   operator=     replaces the logic_error object
                 \fI(public member function)\fP

std::logic_error::logic_error

   logic_error( const std::string& what_arg ); \fB(1)\fP
   logic_error( const char* what_arg );        \fB(2)\fP
   logic_error( const logic_error& other );    \fB(3)\fP (noexcept since C++11)

   1) Constructs the exception object with what_arg as explanatory string. After
   construction, std::strcmp(what(), what_arg.c_str()) == 0.
   2) Constructs the exception object with what_arg as explanatory string. After
   construction, std::strcmp(what(), what_arg) == 0.
   3) Copy constructor. If *this and other both have dynamic type std::logic_error then
   std::strcmp(what(), other.what()) == 0. No exception can be thrown from the copy
   constructor.

.SH Parameters

   what_arg - explanatory string
   other    - another exception object to copy

.SH Exceptions

   1,2) May throw std::bad_alloc.

.SH Notes

   Because copying std::logic_error is not permitted to throw exceptions, this message
   is typically stored internally as a separately-allocated reference-counted string.
   This is also why there is no constructor taking std::string&&: it would have to copy
   the content anyway.

   Before the resolution of LWG issue 254, the non-copy constructor can only accept
   std::string. It makes dynamic allocation mandatory in order to construct a
   std::string object.

   After the resolution of LWG issue 471, a derived standard exception class must have
   a publicly accessible copy constructor. It can be implicitly defined as long as the
   explanatory strings obtained by what() are the same for the original object and the
   copied object.

std::logic_error::operator=

   logic_error& operator=( const logic_error& other );  (noexcept since C++11)

   Assigns the contents with those of other. If *this and other both have dynamic type
   std::logic_error then std::strcmp(what(), other.what()) == 0 after assignment. No
   exception can be thrown from the copy assignment operator.

.SH Parameters

   other - another exception object to assign with

.SH Return value

   *this

.SH Notes

   After the resolution of LWG issue 471, a derived standard exception class must have
   a publicly accessible copy assignment operator. It can be implicitly defined as long
   as the explanatory strings obtained by what() are the same for the original object
   and the copied object.

Inherited from std::exception

.SH Member functions

   destructor   destroys the exception object
   \fB[virtual]\fP    \fI(virtual public member function of std::exception)\fP
   what         returns an explanatory string
   \fB[virtual]\fP    \fI(virtual public member function of std::exception)\fP

   Defect reports

   The following behavior-changing defect reports were applied retroactively to
   previously published C++ standards.

     DR    Applied to          Behavior as published              Correct behavior
   LWG 254 C++98      the constructor accepting const char*   added
                      was missing
                      the explanatory strings of              they are the same as that
   LWG 471 C++98      std::logic_error's                      of the
                      copies were implementation-defined      original std::logic_error
                                                              object
